Vidarabine Vidarabine or adenine arabinoside (CAS 5536-17-4) is an antiviral drug which is active against herpes simplex and varicella zoster viruses. Uniformity white crystalline powder. HPLC and UV not less than 98%.It can be used as pharmaceutical intermediates. we sell pharmaceutical intermediates of vidarabine. You can contact us if you want to order this product. Vidarabine works by interfering with the synthesis of viral DNA. It is a nucleoside analog and therefore has to be phosphorylated to be active. This is a three step process in which vidarabine is sequentially phosphorylated by kinases to the triphosphate ara-ATP. This is the active form of vidarabine and is both an inhibitor and a substrate of viral DNA polymerase. When used as a substrate for viral DNA polymerase, ara-ATP competitively inhibits dATP leading to the formation of ¡®faulty¡¯ DNA. This is where ara-ATP is incorporated into the DNA strand replacing many of the adenosine bases. This results in the prevention of DNA synthesis, as phosphodiester bridges can longer to be built, destabilizing the strand. Vidarabine triphosphate (ara-ATP) also inhibits RNA polyadenylation; preventing polyadenylation essential for HIV-1 and other retroviruses; and S-adenosylhomocysteine hydrolase, preventing transmethylation reactions. Uniquely to vidarabine, the diphosphorylated vidarabine (ara-ADP) also has an inhibitory effect. Other nucleoside analogs need to be triphosphorlated to give any antiviral effect, but ara-ADP inhibits the enzyme ribonucleotide reductase. This prevents the reduction of nucleotide diphosphates, causing a reduction of viral replication.